Apparatus and method for beamforming in a triangular grid pattern

Abstract

A network (26) for feeding a planar array of radiating antenna elements using row beamformers (28) and column beamformers (30) is made to project multiple contiguous antenna beams in a triangular pattern (22). The row beamformers (28) couple to the column beamformers (30). Phase shifting networks (46) are interposed between the row beamformers (28) and column beamformers (30) to apply a phase slope that distributes up to 180° of phase shift across alternating rows of row beamformers (28).

What is claimed is: 
     
       1. A phased array antenna for formation of multiple contiguous antenna beams in a triangular grid pattern, said antenna comprising: a number of antenna elements, said number being equal to the product of M and N, where M and N are integer numbers;   N one-dimensional beamformers wherein each of said N beamformers has M element ports coupled to M of said antenna elements and each of said N beamformers has M beam ports; and   a phase shifting network having N ports, wherein each of said N phase shifting network ports couples to one of said M beam ports from one of said N beamformers and said phase shifting network is configured to implement a phase slope across said N phase shifting network ports.   
     
     
       2. An antenna as claimed in claim 1 wherein: said phase shifting network is a first phase shifting network;   each of said N phase shifting network ports couples to a first one of said M beam ports; and   said antenna additionally comprises a second phase shifting network having N ports, wherein each of said N second phase shifting network ports couples to a second one of said M beam ports from one of said N beamformers, and said second phase shifting network is configured to implement a phase slope across said N second phase shifting network ports.   
     
     
       3. An antenna as claimed in claim 1 wherein: said phase shifting network is a first phase shifting network;   said antenna comprises M/2-1 phase shifting networks in addition to said first phase shifting network; and   each of said M/2-1 phase shifting networks has N ports, wherein each of said N phase shifting network ports of each of said M/2-1 phase shifting networks couples to corresponding ones of said M beam ports from one of said N beamformers and said M/2-1 phase shifting networks are each configured to implement a phase slope across their respective N phase shifting network ports.   
     
     
       4. An antenna as claimed in claim 3 wherein said first and said M/2-1 phase shifting networks implement substantially equivalent phase slopes across their respective N phase shifting network ports. 
     
     
       5. An antenna as claimed in claim 4 wherein each of said first and said M/2-1 phase shifting networks implements a phase slope that slopes to approximately 180 degrees. 
     
     
       6. An antenna as claimed in claim 4 wherein: said M beam ports from said N beamformers are spatially ordered; and   said first and said M/2-1 phase shifting networks couple to alternating ones of said M beam ports from said N beamformers.   
     
     
       7. An antenna as claimed in claim 1 wherein: said beamformers are column beamformers; and   said antenna additionally comprises M row beamformers each having N element ports, each row beamformer element port being coupled to one of said column beamformer, beam ports and said phase shifting network ports.   
     
     
       8. An antenna as claimed in claim 7 wherein: said row beamformer element ports on M/2 alternating ones of said row beamformers couple to said column beamformer beam ports.   
     
     
       9. An antenna as claimed in claim 1 wherein: said antenna elements are positioned in a triangular grid pattern;   said phase shifting network is a first phase shifting network;   said antenna additionally comprises a second phase shifting network having M ports, wherein each of said M second phase shifting network ports couples to each of said M beam ports from one of said N beamformers; and   said second phase shifting network is configured to implement a phase slope across said M second phase shifting network ports.   
     
     
       10. An antenna as claimed in claim 1 wherein: said antenna elements are positioned in a triangular grid pattern;   said phase shifting network is a first phase shifting network;   said antenna additionally comprises N/2 additional phase shifting networks, each of which has M ports, wherein said M phase shifting network ports of said N/2 additional phase shifting networks respectively couple to M beam ports from alternating ones of said N column beamformers;   said N/2 additional phase shifting networks are configured to implement phase slopes across their respective phase shifting network ports; and   each of said N/2 additional phase shifting networks implements one of said phase slopes to approximately 180 degrees.   
     
     
       11. An antenna as claimed in claim 1 wherein said phase shifting network comprises N tunable phase shifters, said N tunable phase shifters being configured to selectively apply and remove said phase slope so that said antenna beams are selectively shifted between said triangular grid pattern and a rectangular grid pattern. 
     
     
       12. In connection with a planar phased array antenna having M row beamformers which communicate signals with N column beamformers where M and N are integer numbers, a method of forming multiple contiguous antenna beams in a triangular grid pattern comprising the steps of: coupling said column beamformers, to a planar array of N times M antenna elements; and   inserting M/2 phase slopes along M/2 of said row beamformers respectively, between said row, and column, beamformers.   
     
     
       13. A method as claimed in claim 12 wherein said M/2 phase slopes are substantially identical to one another. 
     
     
       14. A method as claimed in claim 13 wherein: said method additionally comprises the step of spatially ordering said signals communicated between said N column beamformers, and said M row beamformers; and   said inserting step inserts said M/2 phase slopes along alternating ones of said row beamformers.   
     
     
       15. A method as claimed in claim 12 wherein: said inserting step inserts said M/2 phase slopes using N tunable phase shifters for each of said M/2 phase slopes; and   said method additionally comprises the step of selectively applying and removing said M/2 phase slopes so that said antenna beams are selectively shifted between said triangular grid pattern and a rectangular grid pattern.   
     
     
       16. A method as claimed in claim 12 additionally comprising the steps of: arranging said N times M antenna elements in a triangular grid pattern; and   inserting N/2 element-compensating phase slopes along N/2 of said column beamformers, respectively, said element-compensating phase slopes being inserted between said row, and column beamformers.   
     
     
       17. A planar phased array antenna for formation of multiple contiguous antenna beams in a triangular grid pattern, said antenna comprising: a number of antenna elements, said number being equal to the product of M rows and N columns, where M and N are integer numbers;   N one dimensional column beamformers, wherein each of said N column beamformers has M element ports coupled to M of said antenna elements, and each of said N column beamformers has M beam ports;   M one dimensional row beamformers, wherein each of said M row beamformers, has N element ports, and for each of M/2 of said M row beamformers, said N element ports couple to one of said M beam ports of each of said N column beamformers; M/2 phase shifting networks each of which has N column ports and N row ports, wherein said N row ports of each phase shifting network respectively couple to said N element ports of said M row beamformers, and said N column ports of each phase shifting network respectively couple to one of said M beam ports of each of said N column beamformers;   wherein said M/2 phase shifting networks are each configured to implement a phase slope across its respective ports; and   wherein each of said M/2 phase shifting networks implements a phase slope that slopes to approximately 180 degrees.   
     
     
       18. An antenna as claimed in claim 17 wherein: said antenna elements are positioned in a triangular grid pattern;   said M/2 phase shifting networks are row phase shifting networks;   said antenna additionally comprises N/2 additional column phase shifting networks each of which has M ports, wherein said M ports of said N/2 column phase shifting networks couple to respective ones of said M beam ports from N/2 of said column beamformers;   said N/2 column phase shifting networks are each configured to implement a phase slope across its respective phase shifting network ports; and   each of said N/2 column phase shifting networks implements a phase slope that slopes to approximately 180 degrees.